A short search on CPAN reveals Stephanie Wehners modules, most important Net::ProxyMod.

Another interesting suite of modules is tne Net::PCap suite of modules (also Net::PCapUtils), which gives you access to packet capture and alteration functions of libpcap.

#!perl -w
# usage: portforward configfile
# configfile has lines like this:
#18025 mail.messagingengine.com:25
#18110 mail.messagingengine.com:110
#where 18025 is the TCP port on the local machine and 
#  mail.messagingengine.com:25
#is where that port is forwarded to.

use Socket;
use IO::Socket;
use IO::Select;
use strict;

$| = 1;
my %ports;
my $listen_set =  IO::Select->new();


$SIG{CHLD} = 'IGNORE';

while (<>) {
  chomp;
  my ($localport, $remotehost) = split;
  $ports{$localport} = $remotehost;
  print "config $localport -> $remotehost\n";
  my $socklisten = IO::Socket::INET->new(LocalPort => $localport,
                                   Listen   => 2,
                                   Reuse   => 1,
                                   Proto    => 'tcp')
                         or die "Cannot open sock on $localport: $!\n"
+;
 $listen_set->add($socklisten);
}

my @ready;
print "Parent ready to accept\n";
while (1) {
  @ready = $listen_set->can_read;
  for my $socklisten (@ready) {
    my $socklocal = $socklisten->accept;
    if (defined $socklocal) {
      my ($port, $myaddr) = sockaddr_in(getsockname($socklisten));
      print "accepted on $port\n";
      my $remotehost = $ports{$port};
      if (! defined($remotehost)) {
        print "Internal error on port $port\n";
        die;
      }
      if (fork()) {
        close($socklocal);
      } else {
        close($socklisten);
        my $sockremote = IO::Socket::INET->new(
            Proto     => "tcp",
            PeerAddr  => "$remotehost",
            Timeout   => 30,
         )
         or die "cannot create socketremote($remotehost): $!\n";
         my $buf= ' 'x4096;
         if (fork()) {
           my $sent = 0;
           while (sysread($socklocal,  $buf, 4096)) {
             print $sockremote $buf;
             $sent += length($buf);
           }
           # print "Total bytes sent $sent\n";
         } else {
           my $rcvd = 0;
           while(sysread($sockremote, $buf, 4096)) {
             print $socklocal  $buf;
             $rcvd += length($buf);
           }
           # print "Total bytes rcvd: $rcvd\n";
         }
         exit(0);
      }
    }
  }
}
print "End of parent: $!\n";
__END__
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I am searching for a port forwarding package in perl

Why Perl? (When all you have is a hammer, all your problems start to look like nails).

My basic requirement is to have a platform independent snooping tool between two servers

It sounds to me you want something like Socat. (The site seems to be down at the moment, although it does rate a mention on Freshmeat). Otherwise search around on the web.

socat will do all you want and more. Take the time to learn how to use it, and it will reward you greatly.

I don't know of any network sniffers written in Perl. It should be possible to use libpcap through Net::Pcap. But ethereal or tcpdump would work better.

Hi,

I'm looking for something similar -- I need to see the queries going out from an LDAP client on Windows, to an LDAP server (Oracle OID), and want to use port-fowarding in Perl.

I tried the various examples, but none worked -- in every case, the Perl script just blocked -- it never saw the end-of-transmission and somehow just blocked on the send or receive.

Will this simply not work on Windows? Is there some alternative?

Cheers,

dehansen